December 1st .. The beginning of winter in meteorology

Arab weather - December 1 of every year marks the beginning of winter in the northern hemisphere , according to meteorology, contrary to what is known astronomically as the beginning of winter on 21 or 22 December of each year, the date of the winter solstice .

Why did weather experts create this classification?

• Reason 1 : Facilitate archiving for months, where computers in the past made it difficult to separate the first 20 days of December from the remaining days in terms of weather data, so data entrants took winter information from the first day of December. December .

• Second, weather systems continue to change, according to weather experts. The weather is getting colder, and temperatures are dropping significantly, increasing the chance that the northern part of the globe will be affected by cold air masses.
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What is the definition of moderation and coup .. And the difference between them astronomically

It is noteworthy that the date of December 22 is the beginning of winter in astronomical terms for 2019, where it is the longest night and the shortest day in the northern hemisphere.